Ball Operated Back Pressure Valve
A method for selectively closing a downhole one way check valve, the method having the following steps: attaching the valve to a casing; locking the valve in an open configuration; running the casing and the valve into the wellbore; reverse circulating a composition down an annulus defined between the casing and the wellbore; injecting a plurality of balls into the annulus; unlocking the valve with the plurality of balls; and closing the valve.
The present invention relates to reverse cementing operations useful in subterranean formations, and more particularly, to the use of ball operated back pressure valves in reverse circulation operations.
After a well for the production of oil and/or gas has been drilled, casing may be run into the wellbore and cemented. In conventional cementing operations, a cement composition is displaced down the inner diameter of the casing. The cement composition is displaced downwardly into the casing until it exits the bottom of the casing into the annular space between the outer diameter of the casing and the wellbore. It is then pumped up the annulus until a desired portion of the annulus is filled.
The casing may also be cemented into a wellbore by utilizing what is known as a reverse-cementing method. The reverse-cementing method comprises displacing a cement composition into the annulus at the surface. As the cement is pumped down the annulus, drilling fluids ahead of the cement composition around the lower end of the casing string are displaced up the inner diameter of the casing string and out at the surface. The fluids ahead of the cement composition may also be displaced upwardly through a work string that has been run into the inner diameter of the casing string and sealed off at its lower end. Because the work string by definition has a smaller inner diameter, fluid velocities in a work string configuration may be higher and may more efficiently transfer the cuttings washed out of the annulus during cementing operations.
The reverse circulation cementing process, as opposed to the conventional method, may provide a number of advantages. For example, cementing pressures may be much lower than those experienced with conventional methods. Cement composition introduced in the annulus falls down the annulus so as to produce little or no pressure on the formation. Fluids in the wellbore ahead of the cement composition may be bled off through the casing at the surface. When the reverse-circulating method is used, less fluid may be handled at the surface and cement retarders may be utilized more efficiently.
In reverse circulation methods, it may be desirable to stop the flow of the cement composition when the leading edge of the cement composition slurry is at or just inside the casing shoe. In order to determine when to cease the reverse circulation fluid flow, the leading edge of the slurry is typically monitored to determine when it arrives at the casing shoe. Logging tools and tagged fluids (by density and/or radioactive sources) have been used monitor the position of the leading edge of the cement slurry. If a significant volume of the cement slurry enters the casing shoe, clean-out operations may need to be conducted to ensure that cement inside the casing has not covered targeted production zones. Position information provided by tagged fluids is typically available to the operator only after a considerable delay. Thus, even with tagged fluids, the operator is unable to stop the flow of the cement slurry into the casing through the casing shoe until a significant volume of cement has entered the casing. Imprecise monitoring of the position of the leading edge of the cement slurry can result in a column of cement in the casing 100 feet to 500 feet long. This unwanted cement may then be drilled out of the casing at a significant cost.
SUMMARYThe present invention relates to reverse cementing operations useful in subterranean formations, and more particularly, to the use of ball operated back pressure valves in reverse circulation operations.
According to one aspect of the invention, there is provided a method for selectively closing a downhole one way check valve, the method having the following steps: attaching the valve to a casing; locking the valve in an open configuration; running the casing and the valve into the wellbore; reverse circulating a composition down an annulus defined between the casing and the wellbore; injecting a plurality of balls into the annulus; unlocking the valve with the plurality of balls; and closing the valve.
A further aspect of the invention provides a valve having a variety of components including: a plug removably connected to a housing; a plug seat; and a baffle having a plurality of holes. When the plug is connected to the housing, the valve is in an open position, and fluid may flow through the valve. When the holes in the baffle become plugged, the plug becomes disconnected from the housing and moves into the plug seat, restricting flow through the valve. Another aspect of the invention provides a system for reverse-circulation cementing a casing in a wellbore, wherein the system has a valve and a plurality of balls. The valve may have a plug removably connected to a housing, a plug seat, and a baffle having a plurality of holes. The plug may be connected to the housing, the valve may be in an open position, and fluid may flow through the valve. When the holes in the baffle become plugged, the plug may become disconnected from the housing and move into the plug seat, restricting flow through the valve. The balls may be sized to cause the holes in the baffle to become plugged.
The objects, features, and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the following description of the preferred embodiments.
A more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description of non-limitative embodiments with reference to the attached drawings, wherein like parts of each of the several figures are identified by the same referenced characters, and which are briefly described as follows.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.
DETAILED DESCRIPTIONThe present invention relates to reverse cementing operations useful in subterranean formations, and more particularly, to the use of ball operated back pressure valves in reverse circulation operations.
The valve 1 also has a housing 8 that suspends the plug 7 outside the plug seat 2. The housing 8 has a baffle section 9 (shown more clearly in
When the plug 7 is suspended outside the plug seat 2 of the valve 1, as illustrated in
Referring now to
An example of a reverse cementing process of the present invention is described with reference to
Balls 15 may be used to close the valve 1, when a leading edge 16 of cement composition 17 reaches the valve 1. Balls 15 may be inserted ahead of the cement composition 17 when the cement composition is injected into the annulus at the surface. These balls 15 may be located in a fluid that is just ahead of the cement, or even at the leading edge 16 of the cement. The balls 15 flow down the annulus, around the bottom of the casing 26, and back up into the valve 1 to close it. As shown in
The plug seat 2 and the housing 8 may be attached to a sleeve 3 that will make-up into the casing 26 as an integral part of the casing 26. This allows for casing 26 to be attached below it. The plug seat 2, the housing 8, and the plug 7 may be made of drillable material such as aluminum to facilitate drilling out these components with a roller-cone rock bit if required.
Referring to
The valve 1 may accept a cementing plug 21 in the upper end of the plug seat 2. The cementing plug 21 is illustrated in
Referring to
In one embodiment of the invention, the valve 1 is made, at least in part, of the same material as the sleeve 3. Alternative materials, such as steel, composites, cast-iron, plastic, cement, and aluminum, also may be used for the valve so long as the construction is rugged to endure the run-in procedure and environmental conditions of the wellbore.
According to one embodiment of the invention, the balls 15 may have an outside diameter of approximately 0.75 inches so that the balls 15 may clear the annular clearance of the casing collar and wellbore (e.g., 7.875 inches×6.05 inches). The composition of the balls 15 may be of sufficient structural integrity so that downhole pressures and temperatures do not cause the balls 15 to deform and pass through the holes 14. The balls 15 may be constructed of plastic, rubber, phenolic, steel, neoprene plastics, rubber coated steel, rubber coated nylon, or any other material known to persons of skill in the art.
The present invention does not require that pressure be applied to the casing to deactivate the valve to the closed position after completion of reverse cementing. There may be instances when pumping equipment may not be able to lift the weight of the cement in order to operate a pressure operated float collar or float shoe.
Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.
Claims
1. A method for selectively closing a downhole one way check valve, the method comprising:
- attaching the valve to a casing;
- locking the valve in an open configuration;
- running the casing and the valve into the wellbore;
- reverse circulating a composition down an annulus defined between the casing and the wellbore;
- injecting a plurality of balls into the annulus;
- unlocking the valve with the plurality of balls; and
- closing the valve.
2. The method for selectively closing a downhole one-way check valve of claim 1, wherein the composition is a cement composition.
3. The method for selectively closing a downhole one-way check valve of claim 1, wherein the locking the valve in an open configuration comprises suspending a plug from a housing.
4. The method for selectively closing a downhole one-way check valve of claim 3, wherein the plug is suspended from the housing with one or more shear pins.
5. The method for selectively closing a downhole one way check valve of claim 1, wherein the injecting a plurality of balls into the annulus comprises injecting the plurality of balls at a leading edge of the cement composition.
6. The method for selectively closing a downhole one way check valve of claim 1, wherein the unlocking the valve with the plurality of balls comprises trapping at least a portion of the plurality of balls in a baffle connected to a housing of the valve, wherein the trapped portion of the plurality of balls restricts fluid flow through the baffle.
7. The method for selectively closing a downhole one-way check valve of claim 6, wherein the restricted fluid flow through the baffle causes fluid pressure to move a plug into a plug seat.
8. The method for selectively closing a downhole one way check valve of claim 1, wherein the balls are injected at a leading edge of a cement composition, such that the valve is closed prior to the passage of the cement composition therethrough.
9. A valve comprising:
- a plug removably connected to a housing;
- a plug seat; and
- a baffle having a plurality of holes;
- wherein when the plug is connected to the housing, the valve is in an open position, and fluid may flow through the valve; and
- wherein when the holes in the baffle become plugged, the plug becomes disconnected from the housing and moves into the plug seat, restricting flow through the valve.
10. The valve of claim 9, wherein the plug is removably connected to the housing via one or more shear pins.
11. The valve of claim 9, wherein the holes of the baffle are sized to prevent balls from flowing therethrough.
12. The valve of claim 9, further comprising an O-ring on the plug to further seal the valve and restrict flow therethrough.
13. The valve of claim 9, wherein the seat, the housing, and the plug are comprised of a drillable material.
14. A system for reverse-circulation cementing a casing in a wellbore, the system comprising:
- a valve comprising: a plug removably connected to a housing; a plug seat; and a baffle having a plurality of holes; wherein when the plug is connected to the housing, the valve is in an open position, and fluid may flow through the valve; and wherein when the holes in the baffle become plugged, the plug becomes disconnected from the housing and moves into the plug seat, restricting flow through the valve;
- a plurality of balls, wherein the balls are sized to cause the holes in the baffle to become plugged.
15. The system of claim 14, wherein the balls are located within a cement composition, at a leading edge of the cement composition.
16. The system of claim 14, wherein the balls are located in a fluid just ahead of a leading edge of a cement composition.
17. The system of claim 14, further comprising a cementing plug, such that the system may be used for conventional cementing operations.
18. The system of claim 14, wherein the plurality of balls comprises spheres.
19. The system of claim 14, wherein the plurality of balls comprises spheres comprising an outside diameter of approximately 0.75 inches.
20. The system of claim 14, wherein the seat, the housing, and the plug are comprised of a drillable material.
Type: Application
Filed: Jan 4, 2007
Publication Date: Jul 10, 2008
Patent Grant number: 7533728
Inventors: Donald Winslow (Duncan, OK), Alton Branch (Comanche, OK)
Application Number: 11/619,779
International Classification: E21B 33/13 (20060101);